JSW VIJAYNAGAR- BAR ROD MILL#2

BAR MILL #2 – Specification

Sl.No Parameter Description

01 P d ti it 1.2 Million Tons01 Production capacity (Technology Supplier – Danieli - Italy)

02 Size range Rebar 10 to 40mmg

03 Steel Grades Rebar – FE500D FE550D FE600 & CRS03 Steel Grades Rebar – FE500D, FE550D, FE600 & CRS

04 Cooling QTB (Quenching & Tempering Box)

05 Bundle Weight 2 to 5 tons

06 Bundle Length 6 to 12 mts06 Bundle Length 6 to 12 mts.

BAR MILL #2 – Equipment specification

Sl.No Equipment Description

220T /H01 Reheating Furnace

220Ton/Hr(Technology Supplier – DanieliCentro Combustion - Italy)

02 Water De-scaler 220 Bar Max02 Water De-scaler 220 Bar Max.

03 Roughing & Pre-Finishing Mills 14 Stands

04 Po ered Slitter 10 to 20 mm dia rolling04 Powered Slitter 10 to 20 mm dia rolling.

05 Fast Finishing Block 8 stands for 2 slit lines

06 Bar quenching facilities Water boxes – 4 Nos. each for Slit lines2 Nos for Center lineq g 2 Nos. for Center line.

07 Cooling Bed 102mts.

08 Bundling stations 2 Nos08 & Stackers 2 Nos.

Business Case

• While rolling 16mm rebar, we faced a problem of waviness in finished bar. The finished bar of 16mm wasn’t appear straight after rolling and has slight waviness which affects the product quality.waviness which affects the product quality.

. Project Goals:

• To improve finished bar shape.p p

• To fulfill the product quality requirement as per standard.

Process flow:

Input:1) Billet Furnace Temperature

Process:Rolling stands

Process:1) Rolling.2) Quenching.

TMT Bars

Water Box Flow and PressuresCracks

Output:1) Finished

Surface Defects Blow holes

1) Finished bar rod. Defects: Physical Defects

Mechanical Defects

Waviness

Low YS

Probable causes for waviness In 16Rb

MachineMaterial

Billet chemistry

Billet chemistry Speed

VariationSpeed

VariationUneven billet Uneven billet

Stand SpeedStand Speed

a at oa at o

Cooler internal gap.Cooler internal gap.

Finishing ring rib geometry andFinishing ring rib geometry andWear out nozzleWear out nozzle

temp.temp.Pinch toll ringsPinch toll rings

Waviness in

Finishing ring rib geometry and mass balancing

Finishing ring rib geometry and mass balancing

Wear out nozzle inserts

Wear out nozzle inserts

Quenching nozzle design

Quenching nozzle design

Cooling nozzle Alignment

Cooling nozzle Alignment

finished bar

Keeping low pinch Keeping low pinch

Wrong Cooler installation procedure

Wrong Cooler installation procedure

Furnace Temp. set up

Furnace Temp. set up

Rolling SectionRolling Section

Furnace Gas Furnace Gas p g proll gap

p g proll gap

Furnace Zone Temp

Furnace Zone Temp

Maintaining abnormal furnace temperature

Maintaining abnormal furnace temperatureUneven cooling of

barsUneven cooling of

bars

PressurePressure

Pinch roll profilePinch roll profile

Method Men

Zone Temp.Zone Temp. ppPinch roll profilePinch roll profile

Cause and Effect Matrix :Cause and Effect Matrix :

Xs Sourabh Veeresh Bhuwan Anees Naveen Total Xs Sourabh Veeresh Bhuwan Anees Naveen Total

Uneven billet temp. 3 1 9 3 1 81

Wear out nozzle inserts 3 1 9 3 3 243

Cooling nozzle Alignment 3 0 1 0 1 0

Rolling Section 3 3 1 3 14 27

Billet chemistry 3 1 1 1 3 9

Stand Speed 3 3 1 1 3 27

Furnace Gas Pressure 9 1 3 1 9 243

Quenching nozzle design 9 0 3 0 1 0

Speed Variation 9 1 3 0 9 0

Uneven cooling of bars 1 0 3 1 3 0

Furnace Zone Temp 9 9 9 1 9 6561

Speed Variation 9 1 3 0 9 0

Cooler internal gap. 9 9 9 9 3 19683

Finishing ring rib geometry

Wrong Cooler installation procedure 3 0 3 0 3 0

Pinch roll ring profile 9 9 3 9 9 19683

7

Finishing ring rib geometry and mass balancing 9 9 9 9 9 59049 Pinch roll ring profile 9 9 3 9 9 19683

Probable causes which affects Bar Waviness:

1. Furnace Zone Temperature.

2. Quenching Parameters.

3. Finishing Ring Rib number and their Geometry.3. Finishing Ring Rib number and their Geometry.

4. Wear out nozzle inserts.

5. Pinch roll profile.

Selection matrix:

Idea No Cost of Implement Innovation Time of Ease of TotalIdea No Cost of Implement. Quotient Implem. Implem. Total

1 Low High Low Difficult 38

2 Low High Low Easy 36

3 Low High High Difficult 20g g

4 High High High Difficult 12

5 Low High Low Easy 26

Factors which affects Bar Waviness:Factors which affects Bar Waviness:

1 F T t1. Furnace Temperature.

2. Quenching Parameters.g

Process flow:

Input:1)Furnace Temperature

Process:1) Water Box Flow

Out Put:1) Uniform Martensitic ring1)Furnace Temperature.

2) Rib Geometry.1) Water Box Flow and Pressure.

) gin the core of bar.

2) Straight Bar Rod.

Trail 1: Furnace TemperatureTrail 1: Furnace Temperature

Furnace temperature of Zone 3 & 4 changed from 1160°C to 1135°C and Zone

5 6 & 7 from 1175°C to 1150°C5, 6 & 7 from 1175 C to 1150 C.

Input:1)Furnace Temperature.2) Rib Geometry.

Process:1) Water Box Flow and Pressure.

Out Put:1) Uniform Martensitic

ring in the core of bar. OK2) Rib Geometry. and Pressure. bar.

2) Straight Bar Rod.

Improvedved

Trail 2: Quenching Parameters:Parameters: Water Flow Rate. Water Pressure. Water box cooler setup.Changes: Water flow Rate: We decreased the water flow rate from 980 Qubic mtr per hour to 900 qubic mtr per

hour so that prevent the bar from excess quenching inside the water boxhour so that prevent the bar from excess quenching inside the water box. Water pressure: we increase the water box water pressure 15.5 bar from 14.8 bar by running all 6 nos.

of booster pump to provide rapid quenching of bar inside of water box. Water box cooler setup: we change the water box cooler nozzle setup gap to 6 mm from 8 mm to

decrease the water flow inside the water box for quenching.

Input:1)F rnace Temperat re

Process:1) Water Bo Flo

Out Put:1) Uniform Martensitic

ring in the core of1)Furnace Temperature.2) Rib Geometry.

1) Water Box Flow and Pressure.

ring in the core of bar.

2) Straight Bar Rod.OK

OK

Thank You